Opisthorchiasis is a parasitic disease caused by certain species of genus Opisthorchis (specifically, Opisthorchis viverrini and Opisthorchis felineus). Chronic infection may lead to cholangiocarcinoma, a cancer of the bile ducts.
Medical care and loss of wages caused by Opisthorchis viverrini in Laos and in Thailand costs about $120 million annually. In Asia, infection by Opisthorchis viverrini and other liver flukes affects the poorest people. Along with other foodborne trematode infections such as clonorchiasis, fascioliasis and paragonimiasis, opisthorchiasis is listed among the World Health Organization's list of neglected tropical diseases.
Symptoms of opisthorchiasis are indistinguishable from clonorchiasis. About 80% of infected people have no symptoms, though they can have eosinophilia. Asymptomatic infection can occur when there are less than 1000 eggs in one gram of feces. Infection is considered heavy when there are 10,000-30,000 eggs in one gram of feces. Symptoms of heavier infections may include diarrhea, epigastric and right upper quadrant pain, lack of appetite, fatigue, yellowing of the eyes and skin and mild fever.
These parasites are long-lived and cause heavy chronic infections that may lead to accumulation of fluid in the legs (edema) and in the peritoneal cavity (ascites), enlarged non-functional gallbladder and also ascending cholangitis, which can lead to periductal fibrosis, cholecystitis and cholelithiasis, obstructive jaundice, hepatomegaly and/or portal hypertension.
Both experimental and epidemiological evidence strongly implicates Opisthorchis viverrini infections in the etiology of a malignant cancer of the bile ducts (cholangiocarcinoma) in humans which has a very poor prognosis. Clonorchis sinensis and Opisthorchis viverrini are both categorized by the International Agency for Research on Cancer (IARC) as Group 1 carcinogens.
In humans, the onset of cholangiocarcinoma occurs with chronic opisthorchiasis, associated with hepatobiliary damage, inflammation, periductal fibrosis and/or cellular responses to antigens from the infecting fluke.
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Liver fluke is a collective name of a polyphyletic group of parasitic trematodes under the phylum Platyhelminthes. They are principally parasites of the liver of various mammals, including humans. Capable of moving along the blood circulation, they can occur also in bile ducts, gallbladder, and liver parenchyma. In these organs, they produce pathological lesions leading to parasitic diseases. They have complex life cycles requiring two or three different hosts, with free-living larval stages in water.
Freshwater snails are gastropod mollusks that live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs to major rivers. The great majority of freshwater gastropods have a shell, with very few exceptions. Some groups of snails that live in freshwater respire using gills, whereas other groups need to reach the surface to breathe air. In addition, some are amphibious and have both gills and a lung (e.
Opisthorchis viverrini, common name Southeast Asian liver fluke, is a food-borne trematode parasite from the family Opisthorchiidae that infects the bile duct. People are infected after eating raw or undercooked fish. Infection with the parasite is called opisthorchiasis. O. viverrini infection also increases the risk of cholangiocarcinoma, a cancer of the bile ducts. A small, leaf-like fluke, O. viverrini completes its lifecycle in three different animals.
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